Energy capacity limitation of lithium ion battery (LiBs) has become a bottleneck problem to the emerging field of portable digital electronic devices, moveable electronic devices, and electric vehicles. Although many efforts have been devoted to developing novel anode materials aimed at improving the performance and increasing the capacity of LIBs, including nanostructured silicon, it remains a challenging problem. Recent works have shown that nitrogen-doped graphene can have high reversible capacity and good cycling stability due to high thermal conductivity, high electrical conductivity, good chemical stability, and a high number of activated defects induced by the way the nitrogen atoms are incorporated into the sp2 hybridized carbon network. However, an efficient strategy to achieve a nitrogen-containing carbon nanomaterial with a suitable microstructure and controllable chemical environment for high performance LiBs remains elusive. Graphitic carbon nitride mainly refers to carbon nitride with a 2D layer structure similar to that of graphene. Based on the differences in how the units of the graphitic carbon nitride are constructed, there are two kinds of graphitic carbon nitrides that have been experimentally identified. One is based on triazine units (C3N3), and the other is based on heptazine units (C6N7). In 2009, Wang et al. reported that a heptazine-based graphitic carbon nitride may be a promising photocatalyst for hydrogen evolution by splitting water in visible light (Wang et al., “A metal-free polymeric photocatalyst for hydrogen production from water under visible light,” Nat. Mater., 2009, 8, 76-80).
Recently, Algara-Siller et al. claimed that a triazine-based graphitic carbon nitride is a 2D semiconductor with a direct bandgap of 1.6 to 2.0 eV (Algara-Siller G. et al., “Triazine-Based, Graphitic Carbon Nitride: a Two-Dimensional Semiconductor,” Angew. Chem. Int. Ed., 2014, 53, 1-6). Such a graphitic carbon nitride material could be of particular interest for electronic devices, such as field-effect transistors and light-emitting diodes. The synthesis method used by Algara-Siller et al. is an ionothermal interfacial reaction starting with monomer dicyandiamide. Such a method can only obtain gram-scale products and only one time, so its industrial applications and technological developments are restricted.